Paved Paradise?

Impervious surfaces affect a region's hydrology, ecosystems—even its climate

When raindrops fall on uninhabited terrain, many things can happen. Precipitation that lands on craggy mountainsides flows downhill to streams. Drops that hit soil often soak in; some of that water later evaporates, while much of the rest seeps through the earth to replenish aquifers and nourish springs.